Yet another MS200T issue.

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Vintage Engine Repairs
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Aug 12, 2019
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5,295
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Australia
I've been doing a bit of research for the sake of learning. I didn't realise the check valves in these are a thin piece of plastic? I had a look at the carb cleaner that I'm using and it contains MEK and a load of other things with a specific warning not to use on paint. Probably melted the valves...

Main nozzle check valves are mostly Teflon - highly chemical resistant, you’re fine.

Your current carb is a Zama - here are Zama’s instructions to free a stuck valve....

9E9CBD10-CA69-42AC-8894-20248CAF2A8E.jpeg


Screw in (closed) both L and H carb screws and pop some fuel line over the check valve to make a seal. The gently blow and suck (check valve must be wet to function)

You should hear a gentle pop. Blowing should allow air past, sucking should stop the valve shut.

If there isn’t any popping you have a stuck check valve.

Read the workshop manual for your specific carb to replace the valve if you can’t free it up- it’s cheap and easy. They are pressed / tapped out, but different carbs recommend different directions in which to remove them.
 
paddy1000111

paddy1000111

ArboristSite Lurker
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Well, it was definitely the carb! Put the new carb on and bam, instant acceleration from the get go with 1&1 tuning. I've not had chance to tune it properly tonight as my arms are like jelly after 7 hours of chipping but I also have a quick question for the 200t oracles. When you tune, do you tune to the service manual (set the L jet for the sweet spot at 3600 and then open the L jet to get the rpm down to 2800 then adjust the H) or do you do the other method of adjusting the sweet spot at 2800 and then adjust the H?
 
angelo c
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Not an Oracle but I slept in a holiday inn motel once er two's... I have a tach and its dusty and buried under stuffs...tune by ear. Start with low idle slowly in until it "peaks" then back off a 1/4 turn back. Then high idle until it blubbers. Adjust the manual idle until chain stops. Usually takes some fiddling back and forth between all of the above to get it lean in cut and rich "out" of the cut. I always listen to the saw and watch the cut.


And look up a LOT....
 
lone wolf
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Oct 5, 2009
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Prowling The Pine Barrens
Well, it was definitely the carb! Put the new carb on and bam, instant acceleration from the get go with 1&1 tuning. I've not had chance to tune it properly tonight as my arms are like jelly after 7 hours of chipping but I also have a quick question for the 200t oracles. When you tune, do you tune to the service manual (set the L jet for the sweet spot at 3600 and then open the L jet to get the rpm down to 2800 then adjust the H) or do you do the other method of adjusting the sweet spot at 2800 and then adjust the H?
Just leave it where it is!
 
lone wolf
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Oct 5, 2009
Messages
72,153
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Prowling The Pine Barrens
I'm going to keep my eye out for a really battered 200t and send it to you after running 16:1 motor oil through it with no muffler and a 24" bar.
I can fix it dont worry save your money the prices are up. Dont forget to strip the **** outa all the screws and paint it stupid colors!
 
Vintage Engine Repairs
Joined
Aug 12, 2019
Messages
5,295
Location
Australia
Well, it was definitely the carb! Put the new carb on and bam, instant acceleration from the get go with 1&1 tuning. I've not had chance to tune it properly tonight as my arms are like jelly after 7 hours of chipping but I also have a quick question for the 200t oracles. When you tune, do you tune to the service manual (set the L jet for the sweet spot at 3600 and then open the L jet to get the rpm down to 2800 then adjust the H) or do you do the other method of adjusting the sweet spot at 2800 and then adjust the H?
Wonderful news! Now you can have fun searching for the problem in your other carb :) did you see my message above?
 
Vintage Engine Repairs
Joined
Aug 12, 2019
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Australia
Send that carb to Tom. He thinks he knows a lot about 200t carbs. (even though he has probably never worked on one)

Coming from the one who thought it was an accelerator pump and the carb doesn’t even have one! My advice on checking the metering lever height, pocket valve and welch plugs Is pretty standard stuff which is a great direction in which to go, yours on the other hand is more often than not just unhelpful, rude or in this case totally wrong.
 
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